Synopsis: Granular Flow of a Melting Avalanche

Motion in an ice avalanche is strongly affected by the feedback effect of melting.
Synopsis figure
Daniel Ucko

In September 2002, one hundred million cubic meters of rock and ice separated from the northern slope of the Kazbek massif in North Ossetia, Russia. Traveling at times at nearly 300 km/hour, the resultant avalanche killed dozens of people and caused widespread damage. Ice avalanches from collapsing glaciers are not common in populated areas, but that may change as global temperatures rise. The Ossetia avalanche alerted researchers to the urgency of gaining a better understanding of the processes that control such flows.

In a paper in Physical Review Letters, Barbara Turnbull at the University of Nottingham, UK, tells us how she measured the significant effect of melting on the behavior of ice flows, which therefore differ from dry granular shear flows. In a series of four seemingly simple yet carefully controlled experiments, the author recorded high-speed video of the motion of ice particles that partially fill a slowly rotating narrow drum. The observations appear to confirm that lubrication and capillary action resulting from melting and wetting provide a positive feedback to granular ice flow, like avalanches. Interfacial melting increases flow velocity, which in turn speeds up the melting. However, the real achievement of the reported experiments is that researchers now have a controlled setup with which to study an urgent real-world scenario that has always been difficult to measure. – Sami Mitra


More Features »


More Announcements »

Subject Areas

Nonlinear DynamicsSoft MatterInterdisciplinary Physics

Previous Synopsis

Atomic and Molecular Physics

First Out of the Gate

Read More »

Next Synopsis

Atomic and Molecular Physics

Laser Cooling Tuned to the UV

Read More »

Related Articles

Focus: 3D Images 10 Times Faster
Interdisciplinary Physics

Focus: 3D Images 10 Times Faster

3D x-ray phase-contrast images take as little as one-tenth the usual time to acquire using a technique that halves the number of required “photos.” Read More »

Synopsis: Small Particles Untangle Polymer Chains
Soft Matter

Synopsis: Small Particles Untangle Polymer Chains

Adding nanoparticles to molten polymer disentangles its constituent molecular chains, allowing them to flow more easily. Read More »

Synopsis: How Ice Bridges Form

Synopsis: How Ice Bridges Form

New theoretical work predicts the conditions under which sea ice will clog a narrow channel to create a natural bridge across it. Read More »

More Articles